EEB 3408W MIDTERM #2 REVIEW

CARBON, PHOTOSYNTHESIS & DECOMPOSITION

"Ecosystem Ecology" = study of flow of matter & E within & through system "What controls these processes within ecosystems?" "How do differences across ecosystems influence global patterns in carbon cycling?" "How are humans influencing these processes?"

*Developing theory to explore mechanisms*

"Overyielding" = species mixture produces MORE biomass than expected based on monoculture yields & distributed proportions of component species LV Competition between 2 species: "Overyielding" & stable "Coexistence" = when eq. point ABOVE line that connects carrying capacities (K1 & K2) --abundances = N1* & N2* from eq. point --system at eq. when BOTH growth rates = 0 CAUSE: Over. & Co. => diffs. between species: INTERspecific comp. < INTRAspecific comp. diffs. due to: - diff. resource consumption - consumed by natural predators - existing in diff. places & times - facilitating each other *Competition for ONE limiting resource can produce: 1. SELECTION EFFECTS = Overyielding - homogeneous environment - pool --> species that only differ in R* - **BETTER competitor = LOWEST R* = outcompeting = producing more biomass (obtain limiting resource) 2. COMPLEMENTARITY EFFECTS = Overyielding - heterogeneous environment - pool --> tradoff for 2 nutrients - species competitively superior! - **MORE species invade = DECREASE resource conc. = INCREASE biomass (exploit unconsumed resources)

*Consequences - using food web diagrams to predict outcomes*

"Trophic Cascades" - Changes in abundance of one organism flow vertically through food web w/ indirect interactions "Apparent Competition" - predators mediate competition between two+ prey - predator abundance can alter coexistence between prey (pathogens, mutualisms) *understand introductions & extinctions

SPATIAL INTERACTIONS & COEXISTENCE

"competitive exclusion" = 2 species have completely overlapping niches & CANNOT coexist & one will outcompete other! many factors favor coexistence: - resource partitioning - character displacement - life-history tradeoffs - variable resources - positive species interactions - environmental change cause shifts in INTERspecific interactions

MOVEMENT & METAPOPULATIONS

"metapopulation" = a pop of pops models => predict how likely species will persist/survive in patches of habitat through time

BIODIVERSITY & ECOSYSTEM FUNCTION

"why might we care about how changes in biodiversity influence ecosystem functioning?" -diversifying oversimplified agroecosystems -biodiversity loss in nature - communities quickly recovered = NO increase in resilience - biodiversity = increasing resistance = stable ecosystem productivity

*Main Threats: Species Invasions (5%)*

# arriving in new environ. INCREASES w/ import rate (human movement) trophic interactions (P, H, D) cause extinction: invaders = competitors = INCREASE diversity - interact trophically = REDUCE diversity = extinction

*Modeling disease as DENSITY-dependent* SI

(look at notes in exam #2 desktop folder)

*Modeling disease as FREQUENCY-dependent* SI

(look at notes in exam #2 desktop folder)

*Diff. Photosynthetic Pathways

**C3 plants (ALL PLANTS USE) = CO2 + Rubisco --> sugars - Rubisco low w/ CO2 --> plants invest large amounts N to INCREASE photosynthetic capacity C4 plants = SPATIAL separation of C4 carbon fixaton & C3 fixation = PEP carboxylase => HIGH relationship w/ CO2 (no O2 bind) - REDUCES photorespiration & INCREASES CO2 conc. at Rubisco - LESS sensitive to CO2 (PEP hunts CO2) Benefits: - INCREASE water use efficiency - REDUCTION in N demand (LESS Rubisco) - HIGH light, DRY environ. Cost: - ATP to regenerate PEP *CAM plants - TEMPORAL separation of C4 & C3 carbon fixation *both C4 & CAM plants: => use PEP carboxylase to fix CO2 into 4-C compound --> minimize water loss & photorespiration

*Climate consequences for communities*

**Paleoecology = how organisms respond to biotic/abiotic changes over time reconstruction: - pollen sediment cores from lakes - fossilized plants & animals - genetic data (mitochondrial & chloroplast DNA) - packratmiddens GOAL = if understand the past, able to predict future - abiotic environment = last million yrs: repeated "ice ages" **Palynology = historical vegetation reconstruction (dating core layers) Margaret Davis (1931-present) 1. observed pollen 2. C14 dating of sediment layers 3. knowledge of pollen productivity of species 4. relative pollen buoyancy, etc. **Climate = ice cores --> linking temp + CO2 - ice ages placed by orbital variations biology: organisms RESPOND TO climate! - species associations w/ climate not constant - plants disperse fast like animals climate change: volcanoes, sun, GHGs (forcings = volcanic aerosols, solar variations, GHGs; response = temp) *CLIMATE = AVG.. & VARIATIONS of weather in region over LONG periods of time (EX: decades to millennia) *WEATHER = local combo of conditions (EX: wind, cloud, rain, snow, fog, hurricane, ice storm) at SINGLE point in time

Susceptible-Infected-Recovered (SIR)

*3 equations (S-I-R) i. Threshold density & predicting epidemics "will an epidemic occur?" (look at notes in exam #2 desktop folder) **Threshold host pop density (NT)** = min # susceptible hosts required for transmission - pathogen LOWERS to extinction, unless S > NT - threshold = rate removal / rate infection/transmission - ^^ per capita increase of infectious individuals: dI/Idt = (βS - Y) --> Y/β = S = NT NT = Y/β **Basic reproductive # (R0)** = # infections from intro of infected ind. into ENTIRELY SUSCEPTIBLE pop R0 = βS/Y estimating R0 - transmission coefficient (β) difficult to determine in world -- indirectly estimate R0: R0 = 1+L/A ii. Immunization & "herd immunity" "how much of pop needed vaccinated to prevent epidemic?" R'0 = (1-p)R0 R'0 = (1-p)R0 = 1 p = prop. vaccinated complications disease modeling: - vector borne diseases (EX: malaria, plague, etc) - hosts do not mix evenly (respond to outbreaks = LOWER mixing) - metapops (I & E between isolated pops) - pathogens evolve quickly (need flu shots!)

*Ecological stoichiometry & Redfield Ratio*

*Abundant Elements: Earth's crust - O, Si, Al, Fe, Mg, Ca --> C, H, O, N, P, S *Redfield Ratio: - global marine communities consistent avg. tissue chem. matches environ. C:N:P = 106:16:1 Terrestrial plant C:N:P = 200:13:1 "Homeostasis" = maintenance of eq. elemental ratios within body, despite resource provisioning/E outputs from environ. Consumption --> Biomass/Excretion

*Precipitation*

*Atmospheric Circulation Cells Hadley cells - desert: DRY air, falls Ferrel cells - rain: MOIST air, rises Polar cells - cold: DRY air, falls At any latitude: rainfall MORE in SOUTHERN hemisphere ^oceans/lakes = 81% surface - exposed surfaces = water evaporates MORE (vs bare ground/vegetation)

*Global biodiversity = Speciation - Extinction*

*Biodiversity = # & variety of species & genetic variation contained within each species (species interactions maintaining unique, functioning communities) *Patterns - GLOBAL = diversity greatest near EQUATOR - locations (rainforest, coral reef) --> HIGH diversity of species ~3-20 million known (insects, few viruses/bacteria) *Estimation - Earth's biodiversity range = 2-10 million **Species diversity = Speciation - Extinction (5 major extinction events) *Historical & Current extinction rates Loss of Biodiversity - most species lived = gone extinct (duration: 2-10 my, avg extinction rate last 200 my = 1-2 species/yr!) *"Sixth Mass Extinction" - current estimates ~3-75 species/day! - largest extinction in 65 my!

*Pathogen case studies*

*Case study 1: novel pathogens can lead to extinction (Hawaiian birds) ---avian malaria & loss of mutualists - 33% extinct! --> hunting, habitat destruction, *avian malaria by mosquitoes - loss specialist avian pollinators = 31 species extinction --> disease & vector invasion => cascading extinctions *Case study 2: pathogens can change the outcome of competition ---native disease & invasion vector = R. padi (beetle) virus = BYDV host = perennial/annual grasses EX: CA grassland invasion --> intensive grazing, drought, fire, limited dispersal - decades of grassland management favoring native perennial grass recovery NOT successful due to diseases in grasses! - BYDV enabled invasion of CA grasslands by exotic annuals - disease for structuring communities - exotic invasion controlled by disease presence/absence *Case study 3: loss of pathogens can make invasive species more effective/facilitation ---parasites & invasive species: green crab - parasites: egg predators, trophically-transmitted parasites, parasitoids, parasitic castrators *Disease (INCREASING) & current loss of biodiversity on Earth (DECREASING)*

*Island Biogeography*

*Development of Theory: equilibrium model = rate of change of species richness over time on an island *Tests of Theory: the equilibrium # of species depends on... ISLAND AREA - Extinction = HIGHER on small islands (pop sizes SMALLER) - Immigration = not vary w/ size - Turnover = HIGHER on small islands ISLAND ISOLATION - degree of isolation? - Extinction = not vary w/ isolation - Immigration = HIGHEST closest to mainland (DECREASE w/ distance) - Turnover = HIGHER near mainland Predicting # species: - species' immigration rates change w/ distance from the mainland - species' extinction rates change w/ island size --> simple framework for predicting how many species we should expect to find *Application to conservation questions: - SLOSS => "should we create Single, Large reserve Or Several Small reserves?" - Habitat loss (how many species will go extinct?)

*STAGES OF INVASION: Arrival, Establishment, & Spread*

*Dispersal - global trade & invasion --> # species arriving in new location INCREASES w/ import rate --> human movement affect rates of continental invasion *Traits of good invader 1. broad environmental tolerance (reflected in large geo. range) 2. r-selected life history traits (fast growing, many small propagules, etc.) 3. associations w/ disturbed/anthropogenic (human-dominated) habitats 4. evolutionary origin on large continent w/ diverse biota *r (successful invader): b>d

*Using the past to inform the future*

*Future predictions: - plant taxa that rarely co-occur today are closely associated in past = "no-analog" communities "no-analog" communities: - most common during last deglaciation - late-glacial no-analog communities linked to no-analog climates (highly seasonal)

*Scaling up: GPP & NPP

*GROSS Primary Production: GPP = net rate Caron captured by LEAVES - annual sum net leaf-level photosynthesis over area *NET Primary Production: NPP = net Carbon capture by ENTIRE PLANT - annual net C gain by vegetation over area Main Control: Climate *Net Ecosystem Production: NEP = net Carbon gain of ecosystem - NOT lost through decomp.

*Prevailing Wind*

*Global Currents -Coriolis Effect = Earth rotation deflects surface flows in atm. circulation cells - Tropics = E --> W - USA: Mid-latitudes = W --> E Surface winds + Earth rotation = move ocean water = marine surface currents! (friction) *Rain Shadows (topography) - mountains influence local precip. & temp. **Regional climate = combo of TEMP & PRECIP.

*Summary of Key Biogeo Cycles*

*HYDROLOGICAL - veg capture precip. & prevent from moving into streams & groundwater human alterations: - deforestation (increase runoff) - climate change (alter rain, wind, temp.) - sewage - fertilizer - fishing 5 Elements: 1. Carbon 2. Oxygen 3. Hydrogen 4. *Nitrogen 5. *Phosphorus * = limiting nutrients (shortest supply relative to demand; ADD = INCREASE primary productivity) nutrient SOURCES: net exporters O > I balance: O = I nutrient SINKS: net accumulators O < I *CARBON (GRAPH) - photosynthesis = carbon assimilation/absorption "source" - respiration = carbon efflux/release "sink" *NITROGEN (GRAPH) - amino acids & proteins - source = atm. (pool N2, not usable by plants) - complex (oxidated states) N constantly moving! - atm. N2 oxidized by lightning & bacteria - nitrates & ammonia converted to proteins by plants - N moves plants --> animals (consumption) - proteins --> ammonia --> nitrates --> bacteria - nitrates stored in soil, carried flowing water, --> N2 gas *PHOSPHORUS - NOt abundant/common in atm. --> dissolved in ocean waters (weathering: sedimentary rock & marine sediments) - ATP, NADP, nucelic acids, phospholipids - unlimited source: weathering of rocks - OPEN cycle (marine sediments)

*Photosynthesis*

*Importance: = provides E base for ecosystems **"Primary Productivity" = rate photosynthetic organisms convert E from Sun --> organic & transferable form "Carbon Fixation" = inorganic gaseous carbon (CO2) --> organic carbon compounds (sugars) using E from Sun *Overview of Process: Chloroplast 1. Light rxns 2. Light independent (dark) rxns (carbon fixation) Rubisco => LOW relationship w/ CO2 (plants in high CO2 world) - "Photorespiration" = bind w/ O *Controls: - CO2 - Light - Water (in through roots, out through transpiration) - Temp. - Nutrients 6CO2 + 6H2O + Light E --> C6H12O6 + O2 - Water Availability (decreases w/ CO2 absorption) - Light E = absorbed photosynthetically active radiation (APAR) - Light Availability - Nitrogen (increases w/ net photosynthesis) - Temp. (variations)

*Why do we care about invasive species?*

*Invasion "invasive species" = non-native, economic or environmental harm, propagating in new environ IMPACTS: - 50,000 exotic plants, animals, & microbes - exotic species: --invasions closely linked to extinction --50% U.S. imperiled species threatened by exotics - economic impacts of exotic species very large ($137 billion/yr for control & losses) VS. *Naturalization = INCREASE regional species richness not every new species is pest: - most introduced go extinct in new habitat/environ - naturalized --> persist, NOT dominate in new habitat - some become invasive --> spreads (reducing/driving native species extinction)

*Diversity across space*

*Species-Area = z (slope) - asymptote = regional richness (total species "pool") ***ALPHA = # species in local community - small-scale (within-habitat) diversity ***GAMMA = total # species in region - comprehensive (among-habitat) diversity ***BETA = change (turnover) in species comp. between 2 community samples - between-sample change in composition Gamma = avg. Alpha x Beta

*Global patterns of invasion

*Traits of invasible communities: & environmental responses of invaders: 1. Geographical & historical isolation 2. low diversity of native species 3. high levels of natural disturbance/human activities 4. absence/low diversity of competitors, predators, herbivores, parasites, & diseases (converse = "Biotic Resistance Hypothesis") **plant diversity reduced by nutrients, & where fences reduce light, diversity declines due to native species lost

*Describing landscape structure*

- *heterogeneous (mixed/diff) area composed several ecosystems landscapes/patches vary by: - size - shape - # - composition - position *impacts movement rates

NUTRIENT CYCLING & ECOLOGICAL STOICHIOMETRY

- E lost as heat CANNOT be recycled - matter recycled many times before lost to system - Essential elements: N & P (limit primary productivity) - challenge = getting necessary ratio of nutrients from variable environ. - human additions of N & P = problems in environ. & economy - N deposition DECREASES biodiversity in grasslands -- INCREASES primary productivity rates!

*Resource Partitioning*

- competition varies w/ environment NICHES = range of species' biotic & abiotic tolerances & requirements (separate) - ONLY THIS RANGE ind. can contribute to future generations

*Decomposition/Respiration* = microbial respiration (breakdown organic matter for E & Nutrients)

- conversion dead organic matter --> inorganic nutrients + CO2 *Importance = nutrient recycling, 1st step in soil organic matter formation (soil health: water holding capacity, holding onto other nutrients) Controls Over Litter Decomposition: - strawberries decompose fastest *Overview of Process Factors: 1. Climate Temp. = greater enzyme activity - FASTER decomp. at HIGHER temps. Precip. = - LOW & HIGH moisture = limited decomp. (diffusion) *want MODERATE soil moisture 2. Chem. of organic matter (nutrient content, secondary compounds) - break down through time 3. Soil Organisms (amount/type microbial decomposers, presence macrofauna--earthworms!) - micro- flora & fauna (bacteria, fungi, etc.) - macro-fauna (shredders --> increase surface area for microbes) EARTHWORMS impacts: - No/thin top layer - loss of species diversity on bottom

Metapopulation Model "Levins"

- discrete, identical habitat patches - track occupancy between patches - each patch HIGH risk extinction - dispersal within ALL patches *regional persistence across SPACE --> HIGHER prob persistence = (linear) *regional persistence through TIME --> LESS time = LOWER prob persistence (exponential) *model @ equilibrium: HIGHER occupied patches f = HIGHER rate extinction x

*Main Threats: Habitat Fragmentation + Conversion (44%)*

- habitat = needs of organism (rep. success & survival) = altering physical environ. --> land conversion = FAST change --> USA = 87% endangered species) --> barriers: dispersal, colonization, foraging, breeding small fragments: - lack key resources - altering environ. - increased predators **animals in LARGE habitats lost FIRST *Species comp. of 2 SAME habitats differ in PATCH SIZE

*Main Threats: Disease (2%)*

- impacts <5% threatened/endangered USA species - native/non-native pathogens EX: viruses, bacteria, fungi - Habitat conversion = INCREASE contact rate = INCREASE spread rate EX: Human --> captive animal Wildlife --> human/domestic animals Domestic animals --> wildlife

SPECIES INVASIONS

- new species in environ (natural/invasive) found everywhere (invaders impact regional ecology/economy) - invasive species & invaded communities predictable characteristics - 3 stages invasion: A, E, S - ecological models basis of understanding species invasion - changing abiotic environ (EX: N-dep.) alters species competition (favors invaders)

*Returning to observational studies for generality*

- observations consistent w/ results - science & policy for public

CSR framework

- organisms limited energy, resources & time for SURVIVAL, GROWTH, & REP. in allocation: - resources dedicated to 1 function CANNOT be allotted to another --> MAXIMIZE FITNESS EX: - offspring size & # --> SMALLER size = HIGHER pop - survival & age 1st rep. --> LOWER survival = EARLIER rep. - growth & rep. --> LESS growth = HIGHER rep. effort **Metapopulation models (2 species)** (look at notes in exam #2 desktop folder) SP1 (alone) - c1 = colonization rate SP2 (alone) - c2 = colonization rate - both extinction rate x -- WORSE competitor = BETTER disperser **C-S-R framework** (look at notes in exam #2 desktop folder) Competitor (C) = large fish, perennial herbs/ferns Stress-Tolerant (S) = seahorse, lichens/moss Ruderal (R) = annual herbs, small fish

*Ecology of disease: pathogens, hosts, & environment*

- plague transmission relies on species interactions

*"Community" concept*

- species - pops - communities? "is 'community' an arbitrary designation?" **Gleason = community is ARBITRARY (random choice) "is it a biologically-motivated concept, or simply about how we sample the world?" **Clements = community is REAL "is 'community' USEFUL concept?" - "which processes are responsible for structuring the living world?" & "how do process rates depend on species in a location?" -- reframing to FOCUS ON PROCESSES (biological unit w/ emergent characteristics)

COMMUNITY ECOLOGY

- studying communities requires shift in what's quantified - multi-scale processes = diversity - communities in time, space, re-assembly

*Human Impacts on Biogeo Cycles*

--> Ag. - INCREASED N- & P- cycling "Haber-Bosch Process" - creates NH3 from atm. N2 - ~450 million tons N fertilizer/yr - 1-2% world's annual E supply - MORE THAN DOUBLED quantity N entering biosphere - INCREASE P fertilizer (phosphate rock & manure) - phosphate rock reserves - Eutrophication = marine dead zones :(

*Main Threats: Climate Change (7%)*

1 in 6 species risk of extinction = CO2 increase! Effects: - altered temps. & precip. --> increase weather events, rising sea levels (temp.), increase acidity 1 in 10 species risk extinction by 2100

"How are communities studied?"

1. "community modules" - local pop dynamics - insights into abundance changes w/ time - simplify to 1 location 2. # of species - #/identity of species present --> diff. locations & conditions - simplify to NO pop dynamics 3. abundance of each species - info on abundance of each species --> diff. locations & conditions - simplify to NO pop dynamics

*Movement across landscape*

1. MIGRATION = repeated, round-trip movements 2. DISPERSAL = one-way, permanent movement TYPES: diff. mechanisms 1. Short distance 2. Long distance (EX: coconut falls in water, crawling VS flying) WHY movement?: - resources vary in diff landscapes/seas - organisms need: food, mating, good climate - requirements vary across

*WHY Food Webs?*

1. test hypotheses about interactions - trophic cascades - apparent competition/keystone predation 2. predict consequences of changes (EX: species introduction/extinctions) 3. link ind.-scale interactions to "ecosystem-scale fluxes of E & nutrients" 4. "emergent properties" of structure & functioning of ecosystems 5. generalities & differences in ecosystems 6. how properties of environment influence movement/dynamics

*Biogeographic patterns of diversity*

= # living species known (EX: insects, viruses/bacteria) - Earth's biodiversity range = 3-20 million ~10,000-20,000 NEW species described EVERY year **TRENDS in diversity: 1. INCREASES w/ area surveyed 2. local diversity INCREASES w/ regional 3. INCREASES closer to equator (HIGHEST diversity) 4. DECREASES w/ elevation/latitude 5. INCREASES w/ precipitation 6. DECREASES w/ water depth - observed within groups (EX: amphibians, Lepidoptera, tree species, bivalves, etc.) - ancient pattern (>100my); intensified w/ time ABIOTIC environment => species diversity

**"Koch's Postulates"

= 4 criteria demonstrating disease is caused by particular agent: 1. specific agent associated with all parts of disease 2. agent isolated from diseased host & grown in culture 3. culture-grown agent introduced to healthy susceptible host, agent causes SAME disease (carrying it) 4. same agent isolated from infected host

*The Modern Synthesis*

= Ecological communities: 1. structured via pop processes 2. dynamic & strongly influenced by current environment & historical effects 3. observed associations among species in space & time (not static/deterministic) 4. show directionality & predictability at some spatial/temporal scales 5. do not develop to stable climax

*Main Threats: Pollution (4%)*

= contamination soil, water, atm. from humans (siltation, nutrient inputs/fertilizer, air/water chem.)

*Biomes*

= distinguished by PRE-DOMINANT PLANTS & associated w/ PARTICULAR CLIMATES *Evapotranspiration AET = amount water transitions from L to G state (determined by SUN E) "Actual Evapotranspiration" (AET) = seasonal variations in temp. & precip. = WATER STRESS (environ. niches, plant physiology) *Climate & Dominant Plants (global distribution)

*Main Threats: Overexploitation (size bias/evolution) (37%)*

= extraction "renewable" resources FASTER than replacement - removal LARGEST animals FIRST Overfishing: - DECLINE in pop. (large fish) - commercial extinction (fish species & whales) EX: atlantic cod & right whale Trade of Wildlife: - pleasure - traditional medicine - dramatic declines (animals, plants) - regulated by CITIES - unregulated illegal counterpart ($$$)

*Succession*

=> change in a community over time PRIMARY (ice sheets on mountain) = landscape w/ NO biological legacy/history SECONDARY (prairie) = landscape w/ seeds, roots, &/or live plants

*HOW to depict food webs - diagrams & equations*

=> direct and indirect interactions (diagram & eqs describing WHO eats WHOM) Feeding relations: - direct observations - opening up gut - fecal analyses - DNA metabarcoding

*Building density-dependent disease model*

Assume: recovery + immunity loss

THREATS TO BIODIVERSITY

BIRTH < DEATH Habitat Loss & Conversion (43%)

Carbon Cycle

CO2 INCREASE through time "Carbon flux" = release to atm. Carbon Pools (INPUTS) - Soil = ~1500 Pg - **Atm. = ~750 Pg - **Plant Biomass = ~560 Pg Carbon Fluxes (OUTPUTS) - **Photosynthesis = 120 Pg/yr - Plant Respiration = 60 Pg/yr - Decomposition & Soil Respiration = 60 Pg/yr - Litterfall = 60 Pg/yr

*Conducting experiments to test theory*

Cedar Creek --> Biodiversity experiments "how do changes in biodiversity impact ecosystem functioning?" - MORE species promote ecosystem functioning as MORE years, places, functions, & environ. considered - MANY species needed to maintain multiple functions through times and places in changing world - species = functionally unique (not redundant) - biodiversity impacts ecosystem productivity as much as resources, disturbance, OR herbivory

EARTH'S PHYSICAL SYSTEMS & BIOMES

Climate more hot, wet, & lack seasonality near equator --> Climate driven by SUN! - sun's E interacts with tilt, axial rotation & rotation around sun/orbit --> global patterns: temp., precip., wind, & surface currents - plant types in diff. climate environ. = "biome" Climate + Plant Communities Long-Term Changes: - plate tectonics = distribution land masses change through time - Milankovitch cycles = change distance Earth to Sun

*Metacommunities*

Concept: from Stephen P. Hubbell's "The Unified Theory of Biodiversity & Biogeography" - neutral theory assumptions can recreate observed species abundance distributions - patch & metacommunity framework (applied to wide range of systems) (EX: disease & metapop models similar) - patch scale vary widely (EX: cells, host ind., OR host pops considered patches) "metacommunity" = a community of communities (multispecies analog to metapop concept) --> similar to Island Biogeo; NO MAINLAND) 4 Paradigms: (look at notes in exam #2 desktop folder) Predictions: (look at notes in exam #2 desktop folder)

*Modeling species invasion scenarios*

DIRECT interactions: 1. EXPLOITATION --"Enemy Release Hypothesis" => predators/disease that regulated prey species in native range are absent in exotic range --"(Darwin's) Naturalization Hypothesis" => exotic species unrelated to natives, more likely to successfully invade (do NOT share predators/disease w/ natives) --"Apparent Competition" => invader shares pathogen/predator w/ native species (BUT, less susceptible to attack) 2. COMPETITION --"Empty Niche" => invaders successful when they exploit unused resources (competition w/ natives is minor/absent) --"Novel Weapons" => invader successful --> competitors in new range susceptible to allelopathic compounds --"Soil Feedbacks" => invader modifies soil microbial community to own benefit - positive feedback: invader fosters growth of mutualistic microbes (diff. directions) - negative feedback: invader arrives in environment where pathogens rare (increase w/ time) (cycle)

*How movement affects pop*

EX: Muskrat invasion in Europe (~50 yrs spread, millions) EX: Gypsy moth in N. America, NE USA (accidentally introduced, attack trees)

Food Webs

EX: kelp forest ecosystem - kelp + urchin + sea otter WITH sea otter = more interactions (keystone species) - direct/indirect interacton links - changes in species influence other species/properties - consequences --> introductions, extinctions, etc.

*Climate reconstruction*

EX: tree rings, ice cores, corals, lake & ocean sediments "HOW do species form community?" Biogeography = Alexander von Humboldt (1769 - 1859) *CLEMENTS = "superorganisms", discrete/predictable endpoint/"climax" - "climax community" = static, stable endpoint 1. species linked tightly 2. species cooperate to benefit/support community *GLEASON = "co-located organisms", ind. species-environ interactions, chance historical events - "continuum view" = arbitrary assemblage in space 1. each species has own environ tolerance 2. species respond individualistically to environ Conceptual Models: 1. Facilitation => colonists prepare environ for future successional species (primary succession) 2. Tolerance =>late-successional species arrive early/late, grow slowly, tolerating presence of early-successional species --> outlasting 3. Inhibition => early colonists inhibit subsequent invasion... early colonist dies, resources available for ind (secondary succession) Constraints to plant establishment & growth: - colonization/dispersal ability - availability of limiting soil resources - availability of light - sources of death (EX: herbivores, pathogens) -- 3-way tradeoff between colonization, nutrient competition, & light competition "drives" old- field succession

*Seasonality*

Earth tilt = 23.5° - constant with orbit --> radiation in N. & S. varies seasonally *NORTH tilted towards sun = MORE radiation = WARMER in summer (vice versa in winter)

*Diversity-stability relationships*

Elton: speculation & assertions/beliefs - DIVERSE communities will resist invasion by exotic species & diseases MORE than depauperate communities (lacking variation/# species) May's rigorous theory: - diverse communities will be LESS stable than depauperate communities McNaughton's: clarification - diverse plant communities GREATER stability of community biomass Titan's observations: Cedar Creek - HIGHER density plant communities - productivity lost LESS during drought - MORE fully recovered productivity AFTER drought "Temporal Insurance" hypothesis: - effects enhance temporal mean - reduce temporal variance of ecosystem productivity => species show responses to environ. fluctuations "Theoretical prediction": *INCREASING biodiversity = INCREASING resistance to climate events = INCREASES ecosystem stability = DECREASES pop. stability

*Environmental change & species interactions*

Environmental change: primarily global environmental change drivers: 1. CO2 Enrichment 2. *N Deposition 3. Climate Change 4. Biotic Invasion 5. **Land Use Change *legume-rhizobium mutualism **impact habitat loss: - abundance of single species (best competitor w/ multi species) LOWERED by amount habitat destroyed (PROPORTIONAL) - best competitors extinct FIRST (time INCREASES = LOWER abundance)

*Positive INTERspecific interactions*

Facilitation = - established shrubs provide shade & help establishment of annual grasses - nursery logs provide nutrients & help establishment of other plants - zebra eat long stems, wildebeest medium, gazelles short - species graze in order & each improves food supply for the next

*"why study parasites & pathogens in ecological communities?"* = SPECIES INTERACTIONS!

GOAL = understand & predict DISTRIBUTION & ABUNDANCE of organisms *parasites & pathogens in natural communities: Applications: - do pathogens regulate pops of hosts? - can we predict effect of habitat alteration/climate change on infection risk? - how can we limit spread of a novel parasite? (Will controlling vectors be sufficient?) - what factors lead to emergence & control of new diseases? *species diversity & infection risk: - "DILUTION EFFECT" = infection severity DECLINES w/ host diversity *emerging infectious diseases & multi-species context: EX: malaria, schistosomiasis, lymphatic filariasis, dengue fever, chagas disease, meningitis, cholera, West Nile virus, Lyme disease --> changing environment => altering effects of diseases

*Temperature*

Incoming Energy: - uneven heating of Earth's surfaces (latitudinal variations) - MORE intense radiation near equator (warmer) HIGH latitudes = spread out MORE (larger area)

*Connections to Communities & Carbon Cycle*

N deposition REDUCES species richness - Addition --> diversity loss in grasslands N deposition INCREASES NPP - effects greater than climate & soil - Addition --> INCREASES biomass production in grasslands

*WHAT are Food Webs?*

PAIRWISE INTERACTIONS Sea gulls --> Jonah Crab (bigger; generalist predator feeds on mesopredators & herbivores) --> Crab & Whelk shell --> Mussel

*Long-Term Change: Plate Tectonics & Milancovitch Cycles*

Plate Tectonics - change location of land Long-term changes: Milankovitch Cycles - incoming E varies - High tilt = tilt degrees; warmer summers (strongest at poles) - Precession = axial rotation; seasonality - Eccentricity = orgbital shape

*Modeling pops on landscape*

Pop in 1 patch = HIGH prob. extinction Pop in 2 separate patches = MEDIUM prob. extinction Single patch pop in 2 patches w/ dispersal = prob extinction (~recolonization)

*Conceptions of an ecological "community"*

Population-level processes: - dispersal/arrival - positive pop growth rate -- physiological capacity to persist in abiotic environment -- sufficient access to resources (competition) & refuges (predator-prey/herbivore-plant) *organisms RESPOND TO & ALTER their physical environment - early successional species can tolerate EX: no soil, low nutrients but also get high light, low competition - early arriving species modify environment --> form soil, trap moisture, create shade - w/ changed environment, new species that arrive can establish **identity & traits of species CHANGE w/ environment

Scaling up: Soil Carbon Stocks

Soil carbon builds up when Inputs > Outputs - global warming

*Motivation*

^^^ Charles Darwin: origin of species Ben Ridder: biodiversity conservation **biodiversity INCREASES = ecosystem functioning INCREASES diverse plant communities: - productivity lost less during drought - more fully recovered productivity after drought HIGHER diverse communities: - more productive - consumed more CO2 - more light interfered

*Milankovitch Cycles*

cycles relationship to sun determine patterns of global climate & glacial cycles ECCENTRICITY - amplifies precession) OBLIQUITY (high tilt) - wrmer summers, colder winters (strongest effect at poles!) PRECESSION - affects strength of seasons

*Changing landscape structure: impacts on pops*

humans change: patch size, shape, comp, #, position *fragmentation effects: 1. reduced patch size - LARGER patches = MORE species - size LOWERS = large species w/ larger home areas/ranges LOST FIRST 2. edge effects - fragmentation INCREASES prop. habitat along edges, alters: - "microclimate" (air & soil temp) - susceptibility to invasive species, predators, etc. 3. isolation (INCREASED) - LOWERS recolonization empty patches - LOWERS gene flow - interrupts migration - prevents species shifts in response to climate change

ISLAND BIOGEOGRAPHY & METACOMMUNITIES

local interactions & niches --> no niche overlap = species coexist (specialization in 2 separate niches) --> maintaining diversity (null hypothesis --> "how far can we get if we assume that all species' per capita birth, death, dispersal, and speciation rates are identical?") area INCREASES = species richness INCREASES S = cA^z (slope) log(S) = z*log(A)+log(c) 3 STAGES OF INVASION: 1. Arrival 2. Establishment 3. Local interactions & spread - *I/E rate - *area & distance from mainland - no species diffs/interactions

*Modeling disease: Shifting perspective - tracking infected hosts"

model = track host infection status (similar to meta & P-P) - do not want to track # microbes in host **modeling transmission: 1. DENSITY-dependent βSI - directly transmitted diseases (EX: flu, measles, etc) - Assumption: density ind. INCREASES = INCREASE contact rate 2. FREQUENCY-dependent βSI/(S+I) - vectored/sexually-transmitted diseases (EX: syphilis, malaria, zika, etc) - Assumption: # contacts independent host density (frequency contact)